Is it possible to stop the browser from following the link when the onclick of the child element fires?

Make the javascript method return false!

Or you can also use event.preventDefault() instead of event.stopPropagation()

sure, just return false in the onclick

something like

<a href="somwhere" onclick="return false;">nothing happens</a>

<a href="http://somelink.com">
    <span>stuff</span>
    <span onclick="AwsomeFunction(); return false;">more stuff</span>
    <span>the last stuff</span>
</a>